USCIS has deleted receipt file as per routine maintenace schedule, is there anyway to get copy of I-797 in that case?

Hi Saurabh/Forum members,

I had filed FOIA request to get I-797 of my unstamped H1B, which was approved in 2008. USCIS has provided me whatever information they had, but no proper I-797 document.
They said that receipt notice has been deleted as per their routine maintenace activity.
The pdf document that I have received from USCIS has all information regarding my H1B approval, but consultant says they can transfer only if I provide copy of my I-797.

How can I get copy of my I-797?

Thanks in advance!!